Yes, good point also. It's good not to cause offence somehow, if the person thinks s/he might. Like you say, it might in some circumstances be a good idea to cover them; not a matter of right or wrong, but sensible and respectful, maybe.I do think that it's a plausible situation, but I would also note that if the city dweller with the tattoos were to visit the rural church, they would be advised to cover her tattoos in respect rather than make it a point of pride to fight for her "right" to display them. She may not be wrong to have them, or even show them, but I would place it on the same level that Paul talked about with regards to eating unclean animals in the presence of those that considered such practice to be sin.
The converse is true also; if the 55-year old lady from a rural Baptist church were to go to a city where a contemporary of hers was in a church with short sleeves with some of her ink visible, then she wouldn't necessarily expect her own notions to apply to the city dwellers'.